Dispositions (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Public Utilities, Property, Plant and Equipment, Net	$ 12,729.0	$ 12,232.0
Nonutility Property and Investments, Net	467.0	472.0
Assets, Current	1,221.0	2,145.0
Regulated Entity, Other Assets, Noncurrent	2,089.0	2,003.0
Assets held for sale	0.0	341.0
Liabilities, Current	1,294.0	2,533.0
Liabilities, Noncurrent	3,775.0	3,801.0
Liabilities held for sale		52.0
Estimated pre-tax gain on sale of CGT and SCI	$ 342.0
Assets Held-for-sale [Member] | CGT [Member]
Public Utilities, Property, Plant and Equipment, Net		288.4
Nonutility Property and Investments, Net		0.6
Assets, Current		6.5
Regulated Entity, Other Assets, Noncurrent		0.9
Assets held for sale		296.4
Assets Held-for-sale [Member] | SCANA Communications [Member]
Public Utilities, Property, Plant and Equipment, Net		0.0
Nonutility Property and Investments, Net		40.1
Assets, Current		3.9
Regulated Entity, Other Assets, Noncurrent		0.2
Assets held for sale		44.2
Assets Held-for-sale [Member] | Held for Sale, CGT and SCI [Member]
Public Utilities, Property, Plant and Equipment, Net		288.4
Nonutility Property and Investments, Net		40.7
Assets, Current		10.4
Regulated Entity, Other Assets, Noncurrent		1.1
Assets held for sale		340.6
Liabilities, Held for Sale [Member] | CGT [Member]
Liabilities, Current		3.5
Liabilities, Noncurrent		42.9
Liabilities held for sale		46.4
Liabilities, Held for Sale [Member] | SCANA Communications [Member]
Liabilities, Current		2.2
Liabilities, Noncurrent		3.1
Liabilities held for sale		5.3
Liabilities, Held for Sale [Member] | Held for Sale, CGT and SCI [Member]
Liabilities, Current		5.7
Liabilities, Noncurrent		46.0
Liabilities held for sale		$ 51.7